Model PD6262 Analog Dual-Input Rate/Totalizer Instruction Manual
77
Signal Input Conditioning (
Functn
)
The
Function
menu is used to select the input-to-output transfer function
applied to the input signal: linear, square root, or programmable
exponent. Multi-point linearization is part of the linear function selection.
Each input channel signal input conditioning function is programmed
independently.
Meters are set up at the factory for linear function with 2-point
linearization. The linear function provides a display that is linear with
respect to the input signal.
Square Root Linearization (
Square
)
The square root function is used to calculate flow measured with a
differential pressure transmitter. The flow rate is proportional to the
square root of the differential pressure. Scale the meter so that the low
input signal (e.g. 4 mA) is equal to zero flow and the high input signal
(e.g. 20 mA) is equal to the maximum flow.
Programmable Exponent Linearization (
Prog E
)
The programmable exponent function is used to calculate open-channel
flow measured with a level transmitter in weirs and flumes. The flow rate
is proportional to the head height. Scale the meter so that the low input
signal (e.g. 4 mA) is equal to zero flow and the high input signal (e.g. 20
mA) is equal to the maximum flow. This method works well for all weirs
and flumes that have a simple exponent in the flow calculation formula.
For weirs and flumes with complex exponents it is necessary to use a
strapping table and the 32-point linearization of the meter.
